The Analytical Core provides routine and non-routine analytical service to the University of Iowa research[unreadable] program. The core will provide expert staff, equipment, and instrumentation in line with five Aims. Specific Aim 1[unreadable] is the development of analytical and quality control/assurance standards. In close collaboration with the[unreadable] Synthesis Core, which is responsible for acquiring and archiving individual compound standards and preparing[unreadable] stock solutions, the Analytical Core will develop the mathematical methods for congener representation, analyze[unreadable] single congener solutions for purity assessment and quality control, and test the prepared standard solutions[unreadable] against certified Standard Reference Materials, including PCB calibration mixtures. Specific Aim 2 is the[unreadable] development of a mixture of PCB congeners for laboratory animal exposure studies. The Analytical Core[unreadable] will develop the mathematical methods to design the exposure mixture and test the prepared mixture against[unreadable] certified Standard Reference Materials. Specific Aim 3 is the analysis of environmental and laboratory[unreadable] samples for a suite of PCB congeners (>120). The Analytical Core will extract and analyze PCBs on a[unreadable] congener-specific basis. Applying the primary calibration standard developed under Aim 1, samples will be[unreadable] quantified by the isotope dilution method and the internal standard method. Internal Standards and .Surrogate[unreadable] Recovery Standards developed under Aim 1 will be used to precisely determine PCB concentrations in samples.[unreadable] Methods for analysis on a congener-specific basis will be assessed using performance standard injections and[unreadable] analysis of certified Standard Reference Materials. Some analyses will be performed on the entire suite of PCB[unreadable] congeners, including laboratory animals exposed to the mixture described in Aim 2 and including blood from[unreadable] humans and non-laboratory animals. Other samples will be analyzed for specific congeners and metabolites in[unreadable] support of investigators focused on congener-specific toxicology. Specific Aim 4 involves the extraction,[unreadable] identification, and quantification of unknown metabolites. The Analytical Core will determine purity of[unreadable] synthesized metabolites and associated analytical standards, then analyze for hydroxylated PCBs and other PCB[unreadable] metabolites. As requested by the sbrp investigators, the Analytical Core will also train personnel and assist in[unreadable] sampling design and implementation. Specific Aim 5 is the design and maintenance of a database system. A[unreadable] redundant storage architecture with automatic backup and password protection will be used to allow investigators[unreadable] to download data and reports produced by the Analytical Core.[unreadable]